mmc: sdhci: Add regulator support for vccq (voltage regualor)

On some systems the host controller does not support vccq
signaling.  This is supplied by a dedicated regulator (vqmmc).
Add support for this regulator.
Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -1597,30 +1597,23 @@ static void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
-static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
-						struct mmc_ios *ios)
+static int sdhci_do_3_3v_signal_voltage_switch(struct sdhci_host *host,
+						u16 ctrl)
 {
-	u8 pwr;
-	u16 clk, ctrl;
-	u32 present_state;
-
-	/*
-	 * Signal Voltage Switching is only applicable for Host Controllers
-	 * v3.00 and above.
-	 */
-	if (host->version < SDHCI_SPEC_300)
-		return 0;
+	int ret;
 
-	/*
-	 * We first check whether the request is to set signalling voltage
-	 * to 3.3V. If so, we change the voltage to 3.3V and return quickly.
-	 */
-	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
-	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
 	/* Set 1.8V Signal Enable in the Host Control2 register to 0 */
 	ctrl &= ~SDHCI_CTRL_VDD_180;
 	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
+	if (host->vqmmc) {
+		ret = regulator_set_voltage(host->vqmmc, 3300000, 3300000);
+		if (ret) {
+			pr_warning("%s: Switching to 3.3V signalling voltage "
+				   " failed\n", mmc_hostname(host->mmc));
+			return -EIO;
+		}
+	}
 	/* Wait for 5ms */
 	usleep_range(5000, 5500);
 
@@ -1628,13 +1621,21 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 	if (!(ctrl & SDHCI_CTRL_VDD_180))
 		return 0;
-		else {
-			pr_info(DRIVER_NAME ": Switching to 3.3V "
-				"signalling voltage failed\n");
+
+	pr_warning("%s: 3.3V regulator output did not became stable\n",
+		   mmc_hostname(host->mmc));
+
 	return -EIO;
-		}
-	} else if (!(ctrl & SDHCI_CTRL_VDD_180) &&
-		  (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180)) {
+}
+
+static int sdhci_do_1_8v_signal_voltage_switch(struct sdhci_host *host,
+						u16 ctrl)
+{
+	u8 pwr;
+	u16 clk;
+	u32 present_state;
+	int ret;
+
 	/* Stop SDCLK */
 	clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
 	clk &= ~SDHCI_CLOCK_CARD_EN;
@@ -1648,6 +1649,13 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 		 * Enable 1.8V Signal Enable in the Host Control2
 		 * register
 		 */
+		if (host->vqmmc)
+			ret = regulator_set_voltage(host->vqmmc,
+				1800000, 1800000);
+		else
+			ret = 0;
+
+		if (!ret) {
 			ctrl |= SDHCI_CTRL_VDD_180;
 			sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
@@ -1656,7 +1664,7 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 
 			ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 			if (ctrl & SDHCI_CTRL_VDD_180) {
-				/* Provide SDCLK again and wait for 1ms*/
+				/* Provide SDCLK again and wait for 1ms */
 				clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
 				clk |= SDHCI_CLOCK_CARD_EN;
 				sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
@@ -1673,6 +1681,7 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 					return 0;
 			}
 		}
+	}
 
 	/*
 	 * If we are here, that means the switch to 1.8V signaling
@@ -1692,10 +1701,35 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 	if (host->vmmc)
 		regulator_enable(host->vmmc);
 
-		pr_info(DRIVER_NAME ": Switching to 1.8V signalling "
-			"voltage failed, retrying with S18R set to 0\n");
+	pr_warning("%s: Switching to 1.8V signalling voltage failed, "
+		   "retrying with S18R set to 0\n", mmc_hostname(host->mmc));
+
 	return -EAGAIN;
-	} else
+}
+
+static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
+						struct mmc_ios *ios)
+{
+	u16 ctrl;
+
+	/*
+	 * Signal Voltage Switching is only applicable for Host Controllers
+	 * v3.00 and above.
+	 */
+	if (host->version < SDHCI_SPEC_300)
+		return 0;
+
+	/*
+	 * We first check whether the request is to set signalling voltage
+	 * to 3.3V. If so, we change the voltage to 3.3V and return quickly.
+	 */
+	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330)
+		return sdhci_do_3_3v_signal_voltage_switch(host, ctrl);
+	else if (!(ctrl & SDHCI_CTRL_VDD_180) &&
+			(ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180))
+		return sdhci_do_1_8v_signal_voltage_switch(host, ctrl);
+	else
 		/* No signal voltage switch required */
 		return 0;
 }
@@ -2802,6 +2836,18 @@ int sdhci_add_host(struct sdhci_host *host)
 	    !(host->mmc->caps & MMC_CAP_NONREMOVABLE))
 		mmc->caps |= MMC_CAP_NEEDS_POLL;
 
+	/* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
+	host->vqmmc = regulator_get(mmc_dev(mmc), "vqmmc");
+	if (IS_ERR(host->vqmmc)) {
+		pr_info("%s: no vqmmc regulator found\n", mmc_hostname(mmc));
+		host->vqmmc = NULL;
+	}
+	else if (regulator_is_supported_voltage(host->vqmmc, 1800000, 1800000))
+		regulator_enable(host->vqmmc);
+	else
+		caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
+		       SDHCI_SUPPORT_DDR50);
+
 	/* Any UHS-I mode in caps implies SDR12 and SDR25 support. */
 	if (caps[1] & (SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
 		       SDHCI_SUPPORT_DDR50))
@@ -3122,6 +3168,11 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
 	if (host->vmmc)
 		regulator_put(host->vmmc);
 
+	if (host->vqmmc) {
+		regulator_disable(host->vqmmc);
+		regulator_put(host->vqmmc);
+	}
+
 	kfree(host->adma_desc);
 	kfree(host->align_buffer);
 

include/linux/mmc/sdhci.h

@@ -97,7 +97,8 @@ struct sdhci_host {
 
 	const struct sdhci_ops *ops;	/* Low level hw interface */
 
-	struct regulator *vmmc;	/* Power regulator */
+	struct regulator *vmmc;		/* Power regulator (vmmc) */
+	struct regulator *vqmmc;	/* Signaling regulator (vccq) */
 
 	/* Internal data */
 	struct mmc_host *mmc;	/* MMC structure */